Accelerator of vulcanization



No Drawing.

Patented Oct. 25, 1932 I l UNITED STATES PATENT. OFFICE ALBERT M. onirronn, or AKRON, onro, ASSIGNOB TO THE GOODYEAR TIRE & RUBBER COMPANY, or AKRON, OHIO, A CORPORATION or OHIO ACCELERATOR OF VULGANIZATION rubber. It has particular relation to the provision of a new class of benzothiazyl 2- sulfides for use as vulcanization accelerator-s.

Mercaptobenzothiazole, a. compound having the formula CSH N 3 4 was first prepared by the chemist Hoffman by reacting amino thio phenol with carbon bisulfide. This compound suggested by Hoffman was later found to be an extremely powerful accelerator of vulcanization when incorporated into rubber. Since it may be manufactured quite economically and since it is nontoxic and may be incorporated into rubber with comparative ease, it has become one of the most important of commercial accelerators now upon the market.

This invention comprises the discovery that the simple mercaptobenzothiazole may readily be reacted with certain imids, such as alpha carbo diphenyl di-imid, having the formula C H N=C=N-C H and triphenyl, guanidine, which is also an imid, to produce accelerators which are valuable for certain purposes.

The reaction product of the alpha carbo.

diphenyl di-imid and mercaptobenzothiazole may readily be prepared by heating the two materials in molecular proportions in benzene solution at a temperature of 200 to 220 degrees C. for a period of two or three hours in an autoclave. The reaction product may be obtained by evaporation of the benzene and may be purified by recrystallization from alcohol. It has a melting point of 127 to 130 degrees Application filed May 4, 1931. Serial No. 535,073.

C. The following is the probable formula thereof v O aHaN-H The corresponding reaction product of triphenyl guanidine andmercaptobenzothiazole isobtained by refluxing for a period: of one hour equimolecular quantities of mercaptobenzothiazole and the guanidine in alcohol. Upon concentration of the alcoholic solution, the reaction product is precipitated as a yellow crystalline compound which, upon recrystallization, melts at a temperature of 116 to 118'degrees C. Quantitative analysis of thereaction product indicates that it comprises onemol of thiazole compound with a mol of guanidine. y a The new materialsmay be employed as accelerators of vulcanization in most ofthe standard rubber, compounds. However, the following is a specific example of a compound in which it has been found by experiencethat the materials are quite effective.

' .Barts Rubber .100 ZincoXide 5 Sulfur '3 Steario acid -r 1.5

Accelerator -s 15 varying periods of time. Physical-tests were then conducted upon the vulcanized samples for purposes of ascertaining the tensile strength and elasticity of the. latter$=-The results of these tests are tabulated as fol- 4. Anew chemical compound having the lows: 7 formula e 7 Stress kg s/cln at Q I C V 7 7o ases" awn a Time in Tgmp. 5100% 7100% i Break V 5. A new chenucal compound comprising 7 or the reactlon product of carbo diphenyl di- ALPHA OARBO DIPHENYLWDIIMID DERIVATIVVE or mud and mercaptobenzothmzole.

- MEROAPTOBENZOTHIAZOLE s 7 r p 7 In witness whereof, I have hereunto signed 260 8 32 my name at Akron, 1n the county of Sum- 40 I gag 5; 3 9 3 nut and State of Ohio, U. S; A., this 1st day so 6 v a 7 so 285 23 74 96 740 Of May, 1931. p p 7 p 7 v 7 I I V p A l BERT M; CLIFFORD.

15 TBIPHENYL 'GUANIDINE REACTION'PRODUCT or i; U

MERCAPTOBENZOTHIAZOLE so 0 v p 00 285' 26 e 113 740 I t p p V 85 It will be observed from the tabulated data that whereniercaptobenzothiazole reaction v I p v p r products of either alpha carbo diphenyl di- 7 I p V I 1 9o 25 imid or tri-phenyl guanidine are employed 1 r V 7 as vulcanization accelerators, rubber products having high tensile strength and elasticifiy are obtained within a relatively short 1 taining no, accelerator are either not vulcanized atall or only partially so. 'The new accelerators may be prepared from relatively inexpensive materials and by simple and convenientjmethods. Since the compounds 7 t arev crystalline materials, they may be hantiled in the factory with ease. They are therefore highly desirable, from a commercial viewpoints-ft I I p I e p t 7 "Although I have disclosedanddescribed I m5 in detail only the preferredforms' of the r y s a invention, it will be apparent to those skilled inthe art'that the invention is not limited thereto butthat various modifications may i I be madethereinwithout departing from the w l e i i V 1 no go phenylguanidine.

s irit of the invention or from thescope of the appended c1 aims;-

WhatI claim is: o 1. A, method of treating rubber which I v 1 r comprises subjecting it to vulcanization in y I V j v 7 i l 1 the'presence ofa'carbodiphenyl di-imid re- I l I I v V actionproduct of mercaptobenzothiazole." p A ,method of treating-"rubber which comprises subjecting it to vulcanization in 55' the presenceof'areaction product ofa mate- I rial selected from a class consisting of' rel by 4 i l i J $101) roducts of rnercaptobenzothiazole and carbo diphenyl 'di-imid and reaction 8 products of mercaptobenzothiazole and tri '3.' Arubber product'tha-thasbeen vulcanwed in the presence of a mercaptobznzothiazolefof a material selected from a class con sisting of carbo di-phenyl di-imid and tri- Q5 phenylguanidine. 8'

time; Under similar conditions, stocks cona t 

